Hair curling clip heater



ug. 1, 1950 P. D. SPAETH 2,517,253

HAIR CURLING CLIP HEATER Filed Aug. 20, 1947 N 3 Sheets-Sheet 1 f INVENTOR.

Pff/L D. SPAETH g1 WW y@ INVENTOR. PHIL/p SPA/5TH B971@ P. D. SPAETH HAIR CURLING CLIP HEATER /l/lllllll [lll Aug. l, 1950 P. D. sPAr-:TH 2,517,253

HAIR CURLING CLIP HEATER Filed Aug. 20, 1947 3 Sheets-Sheet 5 INVENTOR. P/f/L/p D. SPAN# Patented Aug. 1, 1950 HAIR CURLINGyCLIPHEATER Philip D. Spaeth, Cincinnati', Ohio Application August 20, 1947, Serial No. 769,668

8 Claims.

The present invention relatestoapparatus for .use in the curling or permanent waving of human '1 hair.

An object of the invention is to incorporate in such yan apparatus ,improved means whereby the formed. in 4a superiormanner,with a minimum of .discomfort to the `person yundergoingl the-hair waving procedure.

' Another object :of the invention is to facilitate -n and expedite the curlingor permanent waving ,operationurelievingthe. operator of strain and fatiene, and'reducine the amount ol skill required yA furthecobject is .to provide apparatus of the character referred to, which is not afected ad- 1- versely by variations in irooin temperature, drafts, and-other..extraneous factors which ordinarily mustl be compensated forin equipmentof other 1 types in orderto obtain the desired results-incil l dent to. permanent waving oi the human hair.

..,.-Another objectY of the invention is to provide paratus of the character described above,-which tishighly durable, efficient, and simple in its operation, ther arrangement being such that-arelai tainaole only by highly skilled and trainedy oper- -atcs upon the. accompanying drawings in which:

l Fig. l, is a perspective View ofthe improved apparatus for the rcurlingorpermanent waving of .human hair.

. Fig.. 2 is a longitudinal cross-sectionalview of ,the'apparatus illustrated by Fig. l.

Fig.. 3- is;acrossfsectionalView taken'onA line di of rig. e.

y, Fig. 5 is a wiring diagram, showing the electrijcal connections -required in the apparatus.

= y Figo is'a schematic view in sideelevation partlybrolrenV away in section showing a heater bar -f f A1 this invention.

The apparatus with which. the ypresent invention is concerned,isgenerally' regarded asa preheat type-oi apparatus, that is, one in which the f 'curling-clips contain no heating'elements or other -meansofgenerating-heatduring the curling op- 2 eration; In the use of the present type of aptively unskilled operatormay produce Vaperma- .'-fnent wave comparable with that heretofore ob- :'-fT-he foregoing and other objects are obtained by the means described herein and illustrated A constructed in -'accordance with an embodiment of rods, the..,curls having been previously saturated .with a. .permanent waving solution as is customary. y' The heated curling clips preferably are of Y inetalof euch-quality and weight as will retain the-necessary amount of heat to complete the .curling orperrnanent.waving of the hair is per- I,s

. permanent waving operation.

AIn apparatus .of the vcharacter mentioned above, itis necessary. to provide suitablev means of elevatine, the.` temperature of the curling clipszto a vspecified degree suitable for waving the hair. In order that the curling clips will be uniformly heated at all times, the machine must not be sen- .f sitive to vchanges in .room temperature, drafts,

Y and other extraneous conditions. lThe use of tl" iostats and similar devices for controlling pre-heattypesof apparatus has generally "been regarded asf-unsatisfactory, since the control iprnentoi` that type is not in direct contact a thefcurling `,clips and therefore does not directly 4.regulate the temperature of the. clips.

Y With the devioe'of the. present invention, the

electricheating element for the clips constitutes part of thecontrolgmeans for temperature,I and byreason ,of thatfact there is attained an im- ,5 mediate compensation for heat loss by the heat- ,.4 ingelements, .as welles vby the curling ,eclips Under this form ofvconstruction, no substantial variation-in 'temperature or the ycurling; clips can .2,occurirrespective.of temperature conditions in l the vicinity of the apparatus. It has neverbeen :possible to Amaintain thek desired uniformity of temperature-inthe curlingiclipsof pre-heat types of apparatus with the useof-therrnostats and the like.

.vltfith referenceto the accompanying drawings, Fig. i illustrates, a current form of the device,

n f .wherein the.,curling vclips l2 are shown applied YHdirectly@ .tothe heatingrods or. bars i3 arranged in spaced parallelism"within a'case or housing M.

The clip supporting rods or bars are supported at oppositeuendsby. means of-ahead member i5 and ia foot inemberfl, so that they arerigidlysup- -ported and thereby constitute firm and substantial supports for theseries otcurling clips i 2 --..applied"thereto. The heatingrods orbars'have ysuitableconnection ywith asource of electric cur- .f rent, andthe-amountoffheat to be radiated thereby may be varied-in any suitable manneigfas by -means opselectorwbuttons I1, i8, and E9s By means vof the several selector buttons, the operator may condition the controls for the heating rodsor .barafto impart thereto a high, medium, or

low- -temperature corresponding wi h the texture of the hairfundertreatment. Thus, the operator is assured ofeausatisfactory-.permanent wave, lby

.- simply -.determining,wliether the hair kundergoing ,treatmentfmayfbe classied as ne,`niedium, or Icoarse;4 The operator-needf'exercise no control kover itin1e,-voltage, or any of the other factors deypending on the `human 'element-for success in the permanent waving? of 'the hair.

i Referring nowfto Fig. 2,"itfmay befnotedthat 3 the heating rods or bars i3 are permanently xedlyv mounted near their opposite ends 20 and 2l, to the foot end` member` I6 and the head end member-I5,"respectively. For this purpose the ends of the rods or bars may be provided with stools 22 to which the bars or rods are welded or permanently iixed in any other suitable manner, the stools in turn being riveted or otherwise securely mounted upon the end members I and I6, as indicated at 23. The heating rods or bars preferably are arranged in a common plane and in spaced parallelism, as indicated, and they are of such proper diameter as to conveniently support the curlingclips I2 with the heads of the clips in full face contact upon the rods or bars for inducing transfer of heat quickly and eiciently from the bars to the clip heads. The curling clips are provided with insulated nger grips I2A vnormally spring-separated to urge the clip jaws Vcient of expansion, Monel metal may be used in forming the body of the rod or bar I3. The body of Monel metal preferably is of tubular form, and constitutes a sheath for heating elements disposed therein. In Fig. 6 a tubular rod I3a of this type is shown schematically. An insulated heating element i313 is located inside the rod I3a. As the temperature of the heating elements within the Monel metal rods or bars is increased, the rods or bars expand lengthwise to increase the distance between the head and foot end members I5 and I6, due to the fact that said members are securely xed to the sheath. The distance between the head and member I5 and the foot end member I6, therefore will depend on the temperature ofthe heating rods or bars. Thus, the distance between the members I5 and I6 at any given temperature, is constant. The contraction and expansion of the heating rods or bars accordingly may be utilized to advantage in controlling the heating of the rods or bars and the curling clips normally supported thereon. To utilize the definite expansion and contraction characteristics of the heating rods or bars for controlling the temperature thereof, the head and foot end members I5 and I6 are mounted within the case or housing for relative movement toward and from one another. The head end member I5 may be bolted as at -24 or otherwise securely fixed to one or more supporting members 25 anchored to the ends of the case or housing at 26 and 21, while the foot end member IE may be slidably supported thereon at the bracket 28. The bracket may consist merely of a metallic ypart apertured to slidablyreceive the supporting means 25. The supporting means accordingly have no restraining effect upon relative movement of the head and foot end members induced by expansion and contraction of the heating rods lor bars I3.

At 30 is indicated a rod-like motion transmitting member supported in parallelism with the 4heating rods or bars I3, this member-30 being i'ixedly secured to the foot end member IB in any suitable manner, as by means of clamping nuts 3l and 32. The motion transmitting member 30 is slidably supported by the head end member I 5, by passing it through an aperture 33 formed therein. This member 3B may be in the form of a rod or tube or Vany suitable material having a very low coeicient of expansion, so that its length is relatively unaffected by changes of temperature. Various materials are available in forming the motion transmitting member 30, and

one Such isa-material oommonly'known as inative movement of the end 34 of member 30 accordingly may be utilized in controlling flow of Yelectric current through the heating rods or bars.

The manner o1 control is most readily evident by referring to Fig. 4, wherein is shown a connection between the free end 34 of the motion transmitting member 30, and a switch actuator 36 which may be in the form of a lever pivoted upon member 30 at the location 31. Lever 36 fulcrums against a pin 38 upstanding upon a bracket 39 xed to the base 35. As the heating rods orbars I3 expand to move the foot end member I6 lengthwise of the supports 25, 4lever 3S will be moved about its iulcrum 38 by the action of the rodlike motion transmitting member 3B. Motion of the lever in the opposite direction may be effected by a suitable spring 8G, as will be explained. Accordingly, the free end M) of lever 36 swings along an arc about the iulcrum 38 whenever changes occur inthe temperature of the several heating rods or bars I3.

The lever SI5 carries at its free end an adjusting screw il which is threaded into a threadedl bore of the lever. The forward end 152 of the adjusting screw is adapted to approach and recede from a switch actuating pin or plunger 43 that extends from the side of the switch housing 44. Within the housing is a movable contact i5 of an electric switch, which contact normally is biased against a stationary contact 46. The switch has a second stationary contact H to be struck by the movable contact arm 45 as the switch plunger d3 is actuated. The electric switch referred to may be one of the type known commercially as a microswitch. r

The adjusting screw 4I may be set to various positions of extension laterally of the switch actuator lever 3S, for the purpose of varying the position at which the lever will be effective to actuate the switch MQ For this purpose, the adjusting screw may be provided at one end with a pinion 48 or any other form of means to effect rotation of the adjusting screw.

As illustrated by way of example, in the accompanying drawings, pinion i8 is to be rotated for rotating the adjusting screw, by reason of its meshing with a gear segment 49 pivoted at 50 upon the head end member of the apparatus. The gear segment has a pin and slot connection 5I with a slide 52, which slide is to be moved to several definite positions within its longitudinal travel limits.

A suitable selector means is provided for use by the operator of the apparatus, to displace the slide 52 to the right or left of the intermediate position assumed by the slide in Fig. 3.- Such means may be in the form of wedge plates 53, 54, and 55 which are attached to the several selector buttons I'I, I8, and I9, respectively. By depressing the selector button Il downwardly against its leaf spring 55, the incline of the wedge 53 strikes a roller or other abutment 5l carried by the side 52, thereby resulting in a shifting movement of the slide to the left in Fig. 3. The slide in moving to the left carries with it the gear sector 49, which rotates the adjusting screw and the pinion :..48 ina counter-clockwisedirection. Thisreposil. tioning of theadjusting screw causes its free end s 42 4to retractlfrom the switchzplunger. 43; thereby requiring the switch actuator` arm or lever to n. move agreaterdistance in order ltoactuate the switch. contact 45.

button I9, wedge. strikes theroller ,dofslide 52, to displace the slide toward the right, .which `vmines the electric currentrequirementsof the Aapparatus.

The case orfhousing may befurnishedwith one or more carrying handles indicatedat 1B. A pilot lamp or other signal I'I is furnished for the purpose of informing theoperator when the curling .clips have reached a proper temperature, so

i that the clips may be removed from the heating results `in, clockwise rotation of the adjusting screwlli and itspinion e5., The adjusting screw I *L1-...when so rotated approaches the switch plunger .43, soi-that very Ylittle .additional movementy f leveri is required for actuating the switch.

The wedge elements 53,y 54, and 55 are normally maintained in an elevated position by means of the springs '5B which yieldingly abut the stems. 5I

that extend through suitable apertures furnished .in the baseplate 35 of the head end member l5.

.. Upward extensions .of the stems carry the push*V buttons Il, la', and I9.

The 'slide 52, as best illustrated by Fig.., 4,

62 and 53 having the several rollers or. abutl' I .slide upon the base 35 'of the head end member.

From the foregoing, it will be understood that actuation of' switch 44 may be governed by the position or" slide 52`as determined by the wedge members of the selector buttons.

As a meansof indicating which of the selector rods, orv bars i3 for use in thev permanent waving operation. The function andoperationofthe a pilot llamp will be explained in greater .detail hereinafter.

Referring to the wiring diagram of Fig. 5, 8| and 82 indicate the electric supply conductorsfor energizing the apparatus. The indicatorlamp .T2 is connected across these conductors by means of the wire 83, so that whenever the main` switch 84 is closed, the lamp will be energized to illuminate one of the several indicia previously referred to herein. Conductcrl is common to the y corresponding ends of all the heating rodsor bars AI3, so thatelectric current may-pass from conductor B I, through all of the heating rods or bars, and find its return by way of a conductor 85 that has, connection with the opposite ends. of all the rods or bars I3. The circuit of thefrods or 'bars is open at the relay contact 86, except when the main switch 84 is closed. Upon closing the l main switch, however, current may ilowI through l, '43 'buttons has been depressed, the member l5 1s..

provided with several windows, one adjacent to each selector button, to' register vwith 'similar windows carried by'an indicator plate B4 that moves with the slide 52. The indicator plate may overlie the head end member as shown upon Figs. 1. and 3,' and movement of the slide 52 may be imparted thereto by means of the upstanding properly register with the windows B9, 10,. and 'Il formed in the head end member I5, as the selector buttons for the respective windows are depressed. The windows .of the indicator plate may, carry' suitablev indicia such as the words Fine,,l\/Iedium, and ,Coarse`: may be applied to suitable transparencies carried The words by the indicator plate 64, so that light` rays from alarnp. I2 beneath the indicator plate may illuminate the indicia as its corresponding windows are aligned by depressing the proper selector but- 30. may comprise a pair of spaced parallel side plates conductors 82, B'l, and 88, to themicrofswitch contacts-46 and 45, the latter being connected to 5 the returnfconductor 8| b mean fthe i .ment-,Str 5t, sa, and en disposed between them. .l y S o Gomeo L The lower edges of'plates 62 and B3 may rest and tion at 89. The circuit which is described in- Accordingly, a flow of electric currentA will be established through all of the heating rods orbars 1 I3.by way of the conductors 82, 86, 85, I3, and 8l.

It will-be recalled that heating of therods or :bars VI3 Vinduces Velongation thereof, so that the motion'transinitting memberll is pulled to the right in Fig. 5, for swinging the switchiactuator Y 35 arcuately in clockwise direction about `the ful- .stationary oontact'll of the .inicro.-switch: 5' The adjusting screw will leave the switchv pin or plunger 43 when the heating rods or bars I5` reach arpredetermined temperature, but the instant at which this occurs is determined by the position of the lever 3S upon the adjusting screw, Aas detemperature, the adjusting screw 4I will be re.

ton. In FigfS, rays from thelamp 'I2 will pass upwardly through the registering windows "fB'I and lll, which previously were aligned by del pressing the middle selector button I8. yToalign depressed forcorrespondingly moving the slide.

As will be understood, eachmovementof the y .slide results in apredetermined rotational Vmovei mentot the'iadjusting. screw 4I,lwhich.deter termined by the depression of the selector buttons II, I8, and I Il, this .having been explained previously in describing theifunction of thetgear sector .49,l slide 52, and the several selector button wedges.

As the heating rodsor bars I3 reach the `desired tracted from the switch pin or plunger 43 by the rocking movement of lever 35, thereby permitting the i micro-switch movable contact 45 lto swing against the opposite stationary Contact 47. yWhen this occurs, an electric circuit `is completed through the conductors 8|, 89, 45,41, 9|, 92,-relay coil 93, conductor 94, and the supply conductor S2. The resulting enengization of therelay 93 effects a closing of the relay contacts 95 and 96, so that current may flow through the pilotlamp 4'll by way of conductors 8l, 99, TI, 58, 95, |002, and

` paratus.

switch contact 46. Thus, no current will flow I through the heating rods or bars I3 until they are reduced in temperature sufficiently to permit swinging of the lever 36V in counter-clockwise direction to the extent of depressing the switch plunger 43, and thereby moving the contact arm 45 against the stationary contact 46. Such closing of the micro-switch at l5- 46 re-establishes the circuit through the main relay winding B, for closing the relay switch contact 86 and restoring the heating cir-cuit.

It will be noted that the forego-ing making and breaking of the heating -circuit for the clip heating rods or bars i3 may continue indefinitely, or

' as longas the main switch -Bll is closed. Moreover, V the pilot lamp II will remain energized throughout such indenite period, since its holding relay `93 is never deenergized except upon breaking the circuit at the main switch 84. In other Words, once the coil of relay 93 is energized to close the contacts 95 and S5, movements of the microswitch contact 45 cannot influence the closed contacts 95 and S6 as these are held closed by the relay coil circuit BI, 91, 95, 92, y951, 94, 82 and t.

As will be understood, the movable contact d5 of the micro-switch is biased by spring means or otherwise, always toward the stationary contact 41, the bias being overcome by depression of the actuating pin or plunger i3 of the switch under the force of spring 8U. Whenever the lever 36 is swung in the direction of spring `BI) by the action of the motion transmitting member 30, the resultant release of pressure upon the pin or plunger I3 permits the movable contact Il of the microswitch to assume its normal position against the stationary contact 41.

From the foregoing it will be understood that the control for maintaining a given temperature kept at a pro-per temperature for application to the curls undergoing treatment. It is therefore impossible to bring about overheating or underheating of the curling clips, even through the apparatus may be exposed to sudden changes of room temperature. y v,

As previously stated herein, the operator of th present apparatus need exercise no control whatever over time, voltage, or any of the other factors subject to human error, in the performance' of the hair waving operation. Success of 'the opm peration is thereby assured, even though the operator may be unskilled or indifferent to the quirements of the procedure. y

It should be understood that the apparatus lherein disclosed is subject to various modilcations and changes in structural details, as it isv obviously possible to eiect various substitutions and equivalents in the construction of the ap- The row of apertures IBI to the left of the selector buttons I'I, I8, and I9 shown upon Fig. '1, provides for the escape of heat from thehead ends of the heating rods or bars I3.

' Whatis claimed is:

the relay coil circuit of relay SII, at the micro- 1. A haii1 curling clip heater comprising in conibination, a plurality of longitudinal heater bars subject to elongation upon heating, said bars being substantially parallel and dimensioned to support thereon a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means fixing opposite end portions of the heater bars securely to said end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar relatively immune to elongation when heated, means fixing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, electrical circuit means including a source of electricity 4and a switch for controlling a flow of electricity through the heater bars, and means associated with said actuator bar for opening and closing the switch and the -circuit controlled thereby.

2. A hair curling clip heater comprising in combination, a plurality of longitudinal heater bars subject to elongation upon heating, said bars being substantially parallel and dimensioned to support thereon -a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means fixing opposite end portions of the heater bars securely to said end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar relatively immune to elongation when heated, means fixing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, electrical circuit means including a source of electricity and a switch for controlling a flow of electricity through the heater bars, and manually adjustable means associated with said actuator bar for opening and closing the switch and the circuit controlled thereby.

3. A hair curling clip heater comprising in combination, a plurality'of longitudinal heater bars subj ect to elongation upon heating, said bars being substantially parallel and dimensioned to support thereon a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means xing opposite end portions of the heater bars securely tosaid end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar spaced below the heater bars and relatively` immune to elongation when heated, means fixing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, an electric circuit including the heater bars, a source of electricity, and a circuit controlling electric switch, and means responsive to relative movements occurring between the free end of the actuator bar and said other end member, for operating the switch to open and close the electric circuit.

4. A hair curling clip heater comprising in combination, a plurality of longitudinal heater bars subject to elongation upon heating, said bars being substantially parallel and dimen- 'sione'd to support thereon a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means xing opposite end por-- tions of the heater bars securely to said end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar spaced below the heater bars and relatively immune to elongation when heated, means xing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, an electric circuit including the heater bars, a source of electricity, and a circuit controlling electric switch, and means responsive to relative movements occurring between the :free end of the actuator bar and said other end mem ber, for operating the switch to open and close the electric circuit, and an adjusting device sem lectively operative to retard and advance the operation of the switch by said responsive means.

5. A hair curling clip heater comprising in combination, a plurality of longitudinal heater bars subject to elongation upon heating, said bars being substantially parallel and dimensioned to support thereon a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means nxing opposite end portions of the heater bars securely to said end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar spaced below the heater bars and relatively immune to elongation when heated, means xing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, an electric switch, a source of electricity, and an electric circuit including the heater bars, the switch, and the source of electricity, said switch being opened and closed by movements of the' free end of said actuator bar.

6. A hair curling clip heater comprising in combination, a plurality of longitudinal heater bars subject to elongation upon heating, said bars being substantially parallel and dimensioned to support thereon a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means i'ixing opposite end portions of the heater bars securely to said end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar spaced below the heater bars and relatively immune to elongation when heated, means iixing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, an electric switch, a source of electricity, and an electric circuit including the heater bars, the switch, and the source of electricity, said switch being opened and closed by movements of the free end of said actuator bar, and means included in the electric circuit for indicating a heated condition of the clip-supporting heater bars.

7. AA hair curling clip heater comprising in combination, a plurality of longitudinal heater bars subject to elongation upon heating, said bars being substantially parallel and dimensioned to support thereon a plurality of displaceable curling clips in heat transferring relationship, a head end member and a foot end member spaced apart, and means fixing opposite end portions of the heater bars securely to said end members whereby expansion of the bars increases the distance between said end members, a motion transmitting means in the form of an elongated actuator bar spaced below the heater bars and relatively immune to elongation when heated, means fixing one end only of said actuator bar to one of said end members, leaving the opposite end of the actuator bar free for relative longitudinal movement with respect to the other end member, an electric circuit including the heater bars, a source of electricity, and a circuit controlling electric switch, and means responsive to relative movements occurring between the free end of the actuator bar and said other end member, for operating the switch to open and close the electric circuit, and an adjusting device selectively operative to retard and advance the operation of the switch by said responsive means, and means included in the electric circuit for indicating heated conditions of the clip-supporting heater bars as determined by said adjusting device.

8. A hair curling clip heater comprising in combination, an elongated heater bar subject to elongation upon heating and adapted to support thereon a plurality of detachable curling clips in heat transferring relationship therewith, spaced head and foot members, and means for rigidly securing the ends of the heater bar to said respective head and foot members whereby relative movement between said end members results in response to changes in length of said bar, a motion transmitting means comprising an elongated actuator bar spaced from the heater bar and relatively immune to elongation when heated, one end of said actuator bar being secured to one of said members and the other end being movable with respect to the other member in response to changes in length of said heater bar, electrical circuit means including a switch for controlling a flow of heating current for said heater bar, and means associated with said actuator bar for opening and closing the switch.

PHILlP D. SPAETH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 867,560 Currey Oct. 1, 1907 1,884,232 Rehm Oct. 25, 1932 1,972,186 Davis Sept, 4, 1934 1,980,475 Davis Nov. 13, 1934 2,060,712 Wright Nov. 10, 1936 2,149,153 Thomsen etal. Feb. 28, 1939 2,159,358 Metz May 23, 1939 2,165,552 Johnson July 11, 1939 2,235,895 Maize Mar. 25, 1941 2,406,693 Jordan Aug. 27, 1946 2,431,904 Andrews Dec. 2, 1947 FOREIGN PATENTS Number Country Date 19,842 Denmark Feb. 5, 1915 

